Inside-caliper gage.



LAnoY s. STARRETT AND JOHN A. ADELL, or ATHoL, MASSACHUSETTS, AssIGNoas-To THE L. s. 'sTARRETT eo., oF ATnoL, MAssAcHUsETTs, -A coRPoRATIoN oF -MA-ssaenu..

SETTS.

No. 905,1 1o. v

g INSIDE-CALIPER GAGE.

Patented Nav. 24, 19,08.

To all whom it may concern:

Be it known that-we, LARoY S. STARRETT and JOHN A. ADELL, both of Athol, in the county of Worcester and` State\of. Massa chusetts, have invented certain new and useful Improvements in Inside-Caliper Gages, of which the following is a specification.

. The object of this invention is to provide a self-ad]usting gage to quickly and accurately take inside measurements .which measurements may be transferred to outside calipers or micrometers by which loose ts,

' tight ts'or shrink lits, in thousandths, may

be correctly determined.

' The invention consists, briefly, 'in a telescoping, spring-actuated and locking lgage of peculiar construction, as herein 1llustrated, described and claimed.

In the drawing, Figure 1 is an elevation of one of these gages, complete. Fig. 2 is an enlarged longitudinal section thereof, and Fig. 3 a view of the grooved'beam-extension detached. Our improved gage consists, essentially, of a tubularbeam or head-portion 6 and its grooved telescoping extension 7, with an inclosed springr. 8;l.tending'to keep said parts in extended position;- vva'=t11bu'lai handle 9 perpendicular to said beamand having at its inner end an internally threaded rigid bush ing`10, also threaded externally at its .ti (which projects slightly-.beyond'suh hande end), tojengage an internally threadedfhub 11, formed on the side of.beamj6;l also anl axial locking bolt 12, in the handle, threaded at tip to engage in bushing 10 and rigidly secured at its outer end to'a rotatable terminal 'plug 13, projecting from' the handle, both beingyknurled externally to facilitate the operation. The Vbeam'extensim 7 has a lonlg'itudinal groove 14with abru (see igs. 2 and 3)', to receive the en of bolt 12 or the adjacent lock-pin 15, heldin 'the slightly enlarged axial'ca'vity atthe end of bushing 10 and actuated .by rotation of l. threaded lock-bolt 12. This movementloeks the parts when the desiredvinternal measurement has been eii'ected, or releases them for further use, the lock-pm end in said groove preventing the beam extension from 'bein thrown' undul koutward b expansion o spring 8. Locit ends,L

pin 15 may e integralwith -ing and provided wit plug for locking and Vreleasing said telescoplock-bolt 12 for this service, but would require either a limited releasing movement of the bolt or a deepler slot in the beam exase 17, see

rounded ends bear against opposite walls.

The parts .are then locked, by rotating bolt 12 by its plug 13, causing the'bolt tip, or

preferably the lockfpin 15, to` bear frictionally in groove 14' ofthe beam-extension, thus retaining the dimension indicated. The gage can then `be tested by a -caliper or any proper measuring instrument, .and the exact lnternal dimension ascertalned.

These gages will naturally be'madein sets of different sizes for use under varying circumstances. The automatic extension feature, controlled by the operators thumb and nger, and the simple lock instantly operative, adapt the device for general use.

We claim as our-invention:

1. The tubular beam, its telesco ing exl tension and inelosed s ring, in com ination with the handle `fixe@ perpendicularly to said beam and with the rotatable terminal plug and locking bolt having a threaded engagement withinl the handle, to lock and to release theftelesco in'g members'. l

2. The tubular Ibeam 6,- ooved telescopi- `ing extension 7 and inclose spring 8, in combination with thetubular handle 9 having a v `rigid bushing 10 fixed perpendicularly to` sald beam, and with the locking bolt' 12 threaded at tip to engage within said busha' rotatable terminal mg parts.

3. The tubular beam .6 and grooved telescoping extension 7 forming with the inthe tubularl ody`9frhavin at its inner/end al fixed bushingv 10 'axia dy perforated and threaded externally an internally, Ksuch loo l closed sprin 8,*the head ofthe instrument;

parts forming the handle, in combination In testimony whereof We have aixed our with locking and releasing means compris-1 signatures, in presence of two witnesses.

ing the threaded lock-bolt' 12 engaging said LAROY S. STARRETT. bushing and havin a projecting, rotatable JOHN A. ADELL. 5 plug, and with the oak-pin' l5 at the tip of Witnesses:

bolt 12 in the bushing perforation, to engage FRANK E. WING, the groove in beam extension 7 WILLARD G. NIMS. 

